Seal With Bellows Type Nose Ring

ABSTRACT

A wellhead assembly having concentric tubulars and a seal assembly in an annulus between the tubulars. The seal assembly includes an upper portion having an annular body with a U-shaped cross section and a nose ring seal. The nose ring seal has a bellows like cross section and provides sealing in the annulus and exerts a lockdown force onto one of the tubulars. Metal inlays are provided on the outer edges of the folds in the bellows and a compressible medium is disposed between the folds.

BACKGROUND

1. Field of Invention

The invention relates generally to a wellbore assembly. More specifically, the invention relates to a bellows shaped nose ring for an annulus seal having pliable material in the folds of the bellows and malleable metal inlays on the edges of its outer folds.

2. Description of Prior Art

Seals are typically inserted between inner and outer wellhead tubular members to contain internal well pressure. The inner wellhead member is generally a hanger for supporting either casing or tubing that extends into the well. Outer wellhead members are usually one of a wellhead housing, or can be a casing hanger when the inner member is a tubing hanger. A variety of seals located between the inner and outer wellhead members are known. Examples of known seals are elastomeric, metal, and combinations thereof and elastomeric rings. The seals may be set by a running tool, or they may be set in response to the weight of the string of casing or tubing. One type of metal-to-metal seal has seal body with inner and outer walls separated by a cylindrical slot, forming a “U” shape. An energizing ring is pushed into the slot in the seal to deform the inner and outer walls apart into sealing engagement with the inner and outer wellhead members, which may have wickers formed thereon. The energizing ring is typically a solid wedge-shaped member. The deformation of the seal's inner and outer walls exceeds the yield strength of the material of the seal ring, making the deformation permanent.

Thermal growth between the casing or tubing and the wellhead may occur, particularly with wellheads located at the surface, rather than subsea. The well fluid flowing upward through the tubing heats the string of tubing, and to a lesser degree the surrounding casing. The temperature increase may cause the tubing hanger and/or casing hanger to move axially a slight amount relative to the outer wellhead member. During the heat up transient, the tubing hanger and/or casing hanger can also move radially due to temperature differences between components and the different rates of thermal expansion from which the component materials are constructed. If the seal has been set as a result of a wedging action where an axial displacement of energizing rings induces a radial movement of the seal against its mating surfaces, then sealing forces may be reduced if there is movement in the axial direction due to pressure or thermal effects. A reduction in axial force on the energizing ring results in a reduction in the radial inward and outward forces on the inner and outer walls of the seal ring, which may cause the seal to leak. A loss of radial loading between the seal and its mating surfaces due to thermal transients may also cause the seal to leak. One approach to preventing this type of movement is through the use of lockdown C-rings on the seal that rest in a machined pocket on the energizing ring. The C-ring engages the hanger when the seal is set, locking the seal to the hanger. Another approach has been to use the sealing element itself as a locking mechanism. In these approaches, lockdown is thus provided by the seal. Further, a lockdown style hanger may be utilized to lock the casing hanger in place. This requires an extra trip to lower the lockdown style hanger.

SUMMARY OF THE INVENTION

An example of a seal assembly for use between concentric downhole tubulars is described that includes an annular upper portion that has a ring like outer leg, a ring like inner leg set radially inward from the outer leg that defines an annular space between the inner leg and outer leg, and a lower end attached to the outer leg. The seal assembly includes a nose ring assembly coupled to a lower end of the upper portion. The nose ring assembly includes an annular seal body having a bellows shaped cross section. The seal body has folds with edges along inner and outer circumferences of the seal body. Metal inlays are on the edges and compressible material is between the folds. When the seal assembly is disposed between the concentric downhole tubulars and an end of an energizing ring is inserted into the annular space between the inner and outer leg, the seal body of the nose ring transfers a lock down force onto one of the tubulars and the edges extend radially inward and outward into sealing contact with the downhole tubulars. Optionally, the compressible material has encapsulated gas dispersed within a medium. In one example, glass microspheres form the encapsulated gas and the medium is made of an elastomer. In one alternate embodiment, the seal body is made of an elastic metal. The metal inlays can be made from a metal having a yield strength less than the downhole tubulars, so that when the edges extend into sealing contact with the downhole tubulars and discontinuities are present on the downhole tubulars, the inlays conform to the discontinuities to provide the sealing contact. The seal body of the nose ring may be threadingly coupled to the upper portion. Optionally, the seal assembly can further include a ring like lower base projecting axially downward from an end of a lowermost fold, wherein the lower base is in selective contact with a casing hanger. A lock nut may be optionally included that is mounted on an inner surface of the upper end of the upper portion, so that when the energizing ring is pulled from between the tubulars, the seal assembly is retrieved with the energizing ring.

Also provided herein is an example of a wellhead assembly that includes an outer tubular, an inner tubular inserted within the outer tubular to define an annular space between the tubulars; and a seal assembly in the annular space. The seal assembly includes a seal body having axially projecting folds that define a bellows and edges between adjacent folds that are in sealing contact with an outer surface of the inner tubular and an inner surface of the outer tubular. An upper end of the folds is engaged to one of the outer tubular or lower tubular and a lower end engaged with the one of the tubulars not engaged by the upper end. When the seal assembly is set in the annular space, a lock down force is transmitted between the inner and outer tubulars through the seal body. A compressible material may be disposed between the folds. In one example, the compressible material is made up of glass microspheres dispersed in an elastomeric medium. An upper portion may be included that is attached to an upper end of the seal body. The upper portion may include an annular outer leg in engagement with the outer tubular and an inner leg spaced radially inward from the outer leg that has a lower end depending from the outer leg and is in contact with the inner tubular. Optionally, a lower base may be included on the seal body that contacts the inner tubular and transmits the lock down force from the inner tubular to the seal assembly. In an example embodiment, metal inlays are provided on the edges that conform to discontinuities on the respective surfaces of the inner and outer tubulars.

Also provided herein is an example of a seal assembly for use between concentric inner and outer downhole tubulars that includes an annular lockdown portion having a ring like outer leg and a ring like inner leg set radially inward from the outer leg that defines an annular space between the inner leg and outer leg. A lower end of the outer leg attaches to the outer leg. A nose ring assembly couples to a lower end of the lockdown portion that is made up of a bellows like annular seal body that with folds that are at an oblique angle to adjacent folds. Edges are formed at interfaces between adjacent folds that extend along inner and outer circumferences of the seal body. Metal inlays are provided on the edges and compressible material is set between the folds. The compressible material is made of an elastomeric substrate with glass microspheres dispersed in the substrate. In this way when the seal assembly is disposed between the concentric downhole tubulars and an end of an energizing ring is inserted into the annular space between the inner and outer leg, the seal body of the nose ring transfers a lock down force onto one of the tubulars and the edges extend radially inward and outward into sealing contact with the downhole tubulars. The seal body can be made of an elastic metal. In one example embodiment, the metal inlays are made from a metal having a yield strength less than the downhole tubulars so that when the edges extend into sealing contact with the downhole tubulars and discontinuities are present on the downhole tubulars, the inlays conform to the discontinuities to provide the sealing contact. The seal body of the nose ring can be threadingly coupled to the lockdown portion and may further include a ring like lower base projecting axially downward from an end of a lowermost fold, wherein the lower base is in selective contact with a casing hanger.

BRIEF DESCRIPTION OF DRAWINGS

Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side partial sectional view of an example embodiment of a seal assembly between downhole tubulars in accordance with the present invention.

FIG. 2 is a detailed portion of the embodiment of FIG. 1.

FIG. 3 is a sectional view of an embodiment of the seal assembly of FIG. 1 in a locked configuration in accordance with the present invention.

FIG. 4 is a side partial sectional view of a wellhead assembly having an embodiment of a seal assembly in accordance with the present invention.

While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF INVENTION

The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout.

It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the improvements herein described are therefore to be limited only by the scope of the appended claims.

An example embodiment of a wellhead assembly 20 is shown in a side partial sectional view in FIG. 1. In the example of FIG. 1, the wellhead assembly 20 is shown having an annular hanger 22 coaxially disposed within an annular housing 24. The hanger 22 may be one of a casing hanger or a tubing hanger, wherein the housing 24 can be one of a high pressure housing or casing hanger. A seal assembly 26 is shown set within an annular space between the concentric hanger 22 and housing 24. The seal assembly 26 includes a seal member 28 on its upper end. In the example of FIG. 1, part of the seal member 28 is a ring-like outer leg that runs substantially in an axial direction and adjacent an inner surface of the housing 24. An inner leg is included with the seal member 28 that is set radially inward from the outer leg to define a space therein. The inner leg is connected to the outer leg by a lower end that projects radially inward from the outer leg and then axially upward to the inner leg.

A nose ring assembly 30 is shown mounted on a lower end of the seal member 28 and beneath the inner leg. Partially coaxially within the seal member 28 is an annular energizing ring 32, having a lower wedge-shaped extension shown inserted in the space between the outer and inner legs of the seal member 28. In the example of FIG. 1, ridge-like wickers 34 are shown formed respectively on the outer surface of the hanger 22 and inner surface of the housing 24. An annular lug ring 37 is shown threadingly secured to an upper end of the seal member 28 that extends radially inward from the seal member 28. As described in more detail below, by axially urging the nose ring 32 downward so its lower end inserts into the space between the inner and outer legs of the seal member 28, sealing may take place within the annular space between the hanger 22 and housing 24. Moreover, the lug ring 37 extends radially inward from the seal member 28 and interferes with a ledge on the energizing ring 32 when the energizing ring 32 is pulled upward to also pull on the seal member 28.

Referring now to FIG. 2, a portion of the embodiment of FIG. 1 is shown in a side partial sectional view and in greater detail. More specifically, FIG. 2 depicts that a bellows-like nose ring body 38 is included with the nose ring assembly 30 along with a lower base 40 on the lower end of the body 38. In the example of FIG. 2, the lower base 40 is a generally ring-like annular member and configured to land on a ledge 41 (FIG. 1) provided on the hanger 22. An upper base 42 is shown mounted on an upper end of the nose ring body 38 and is also a generally ring-like annular member. A portion of the upper base 42A is threaded for attachment to the seal member 28. In the example of FIG. 2, the nose ring body 38 is made up of a series of folds 44 shown arranged generally oblique to each adjacent fold 44. Edges 45 are defined on the body 38 where the adjacent folds 44 join. On the outer surface of the edges 45 are optional metal inlays 46 that in an example are formed from a metal that is softer (i.e., having a lower yield strength) than that of the hanger 22 and housing 24. In one example embodiment, the metal inlay 46 includes tin indium. In the embodiment of FIG. 2, a mid portion of the edges 45 is recessed for receiving the inlays 46, the recesses define points 47 on the upper and lower ends of the edges 45 that penetrate into and grip the hanger 22 and housing 24 when the body 38 axially compresses.

Each adjacent fold 44 defines a wedge-shaped space in which is disposed a compensating material 38. The compensating material 38 provides a barrier to debris and other undesirable material that may otherwise enter into the space between the folds 44. In one example embodiment, the compensating material 48 is shown having a series of spheres 50 that are dispersed within a substrate 52. Examples of spheres 50 include a compressible fluid, such as a gas, encapsulated inside of a load-bearing housing, such as a glass microsphere. The substrate 52 may include elastomeric materials, such as foam, rubber, composites, and the like.

In the example embodiment of FIG. 3 the seal assembly 26 is in an energized and sealing configuration. As shown, the energizing ring 32 is axially inserted within the legs of the seal member 28 thereby projecting the legs of the seal member 28 radially apart from one another and into contact with the housing 24 and also the hanger 22. In a typical installation, the wickers 34, 36 in the housing 24 and the hanger 22 form corresponding grooves 54, 56 on the inner and outer legs of the seal member 28. Additionally, the downward urging of the lockdown ring 32 transmits a lock down force through the seal member 28 and onto the nose ring assembly 30 for preventing respective axial movement of the hanger 22 and housing 24. Referring back to FIG. 2, in an example embodiment, the contact between the upper and lower bases 40, 42 of the nose ring body 38 transmits force from the hanger 22 and the housing 24. While the bellows portion of the nose ring body 38 axially deforms, sufficient axial stresses remain within the nose ring assembly 30 to maintain the lockdown force between the hanger 22 and housing 24.

When the seal assembly 26 is in the set position of FIG. 3, the axial deformation of the nose ring body 38 allows the edges 45 to move radially inward and outward into contact with the respective outer and inner surfaces of the hanger 22 and housing 24. With sufficient inward and outward radial force, the softer metal inlays 46 on the edges 45 deform and create sealing contact between the nose ring body 38 and surfaces of the hanger 22 and housing 24. Discontinuities 58, such as scratches, scores or other damage, may be present on one of the sealing surfaces of the hanger 22 or housing 24. The deforming metal inlays 46 can fill the space of the discontinuity 58, thereby ensuring a sealing surface within the annulus between the hanger 22 and housing 24. Moreover, the spheres 50 within the compensating material 48 may collapse and the encapsulated gas in the spheres 50 will compress in response to the forces (and pressures) encountered while energizing the seal assembly 26. The collapsing spheres 50 and compression of the gas allows axial compression of the nose ring body 38. Thus, should any liquid 59, such as from the wellbore, enter the space between adjacent folds 44, the compensating material 48 compresses to make up for the presence of the liquid 59 so that movement of the folds 44 is not restricted when the seal assembly 26 is being energized.

FIG. 4 illustrates a side partial sectional view of one example of a wellhead assembly 20 that is mounted over a wellbore 60. In the example of FIG. 4, the wellhead assembly includes a production tree 62 mounted on a wellhead housing 64. Casing 66 depends downward from the wellhead assembly 20 and into the wellbore 60. The casing 66 is shown concentrically around a string of production tubing 68 that also depends into the wellbore 60. In the example of FIG. 4, the seal assembly 26 is inserted between the casing hanger, on which the casing 66 is supported and a high pressure wellhead housing 24. In one example of use, the seal assembly 26 described herein may be used in an emergency situation wherein an initial seal has failed. In such an example, deformations, such as the discontinuities 58 of FIG. 3, may be present within one or more of the tubulars in the wellbore 60. Moreover, the wickers 34, 36 may have also been damaged, thereby compromising the sealing ability of a seal, such as seal member 28. In this example, implementing a nose ring as described herein can provide sealing capabilities to overcome the sealing problems encountered. An advantage of the nose ring described herein is that it can be integrated with the standard seal member 28 and installed using steps typically undertaken to install the seal member 28.

The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims. 

What is claimed is:
 1. A seal assembly for use between concentric downhole tubulars comprising: an annular upper portion comprising a ring like outer leg, a ring like inner leg set radially inward from the outer leg to define an annular space between the inner leg and outer leg and having a lower end attached to the outer leg; and a nose ring assembly coupled to a lower end of the upper portion comprising an annular seal body having a bellows shaped cross section that defines folds having edges along inner and outer circumferences of the seal body, and compressible material between the folds, so that when the seal assembly is disposed between the concentric downhole tubulars and an end of an energizing ring is inserted into the annular space between the inner and outer leg, the seal body of the nose ring transfers a lock down force onto one of the tubulars and the edges extend radially inward and outward into sealing contact with the downhole tubulars.
 2. The seal assembly of claim 1, wherein the compressible material comprises encapsulated gas dispersed within a medium.
 3. The seal assembly of claim 2, wherein the encapsulated gas comprises glass microspheres and the medium comprises an elastomer.
 4. The seal assembly of claim 1, wherein the seal body comprises an elastic metal.
 5. The seal assembly of claim 1, further comprising inlays that comprise metal having a yield strength less than the downhole tubulars, so that when the edges extend into sealing contact with the downhole tubulars and discontinuities are present on the downhole tubulars, the inlays conform to the discontinuities to provide the sealing contact.
 6. The seal assembly of claim 1, wherein the seal body of the nose ring is threadingly coupled to the upper portion and further comprises a ring like lower base projecting axially downward from an end of a lowermost fold, wherein the lower base is in selective contact with a casing hanger.
 7. The seal assembly of claim 1, further comprising a lock nut mounted on an inner surface of the upper end of the upper portion, so that when the energizing ring is pulled from between the tubulars, the seal assembly is retrieved with the energizing ring.
 8. A wellhead assembly comprising: an outer tubular; an inner tubular inserted within the outer tubular to define an annular space between the tubulars; and a seal assembly in the annular space comprising: a seal body having axially projecting folds that define a bellows and edges between adjacent folds that are in sealing contact with an outer surface of the inner tubular and an inner surface of the outer tubular, and an upper end engaged to one of the outer tubular or lower tubular and a lower end engaged with the one of the tubulars not engaged by the upper end, so that when the seal assembly is set in the annular space, a lock down force is transmitted between the inner and outer tubulars through the seal body.
 9. The wellhead assembly of claim 8, further comprising a compressible material disposed between the folds.
 10. The wellhead assembly of claim 9, wherein the compressible material comprises glass microspheres dispersed in an elastomeric medium.
 11. The wellhead assembly of claim 8, further comprising an upper portion attached to an upper end of the seal body, the upper portion comprising an annular outer leg in engagement with the outer tubular and an inner leg spaced radially inward from the outer leg that has a lower end depending from the outer leg and is in contact with the inner tubular.
 12. The wellhead assembly of claim 11, further comprising a lower base on the seal body that contacts the inner tubular and transmits the lock down force from the inner tubular to the seal assembly.
 13. The wellhead assembly of claim 8, further comprising metal inlays on the edges that conform to discontinuities on the respective surfaces of the inner and outer tubulars.
 14. A seal assembly for use between concentric inner and outer downhole tubulars comprising: an annular lockdown portion comprising a ring like outer leg, a ring like inner leg set radially inward from the outer leg to define an annular space between the inner leg and outer leg and having a lower end attached to the outer leg; a nose ring assembly coupled to a lower end of the lockdown portion comprising: a bellows like annular seal body that defines folds that are obliquely angled to adjacent folds, edges formed at interfaces between adjacent folds that extend along inner and outer circumferences of the seal body, and compressible material between the folds that comprises an elastomeric substrate with glass microspheres dispersed in the substrate, so that when the seal assembly is disposed between the concentric downhole tubulars and an end of an energizing ring is inserted into the annular space between the inner and outer leg, the seal body of the nose ring transfers a lock down force onto one of the tubulars and the edges extend radially inward and outward into sealing contact with the downhole tubulars.
 15. The seal assembly of claim 14, wherein the seal body comprises an elastic metal.
 16. The seal assembly of claim 14, further comprising inlays that comprise metal having a yield strength less than the downhole tubulars, so that when the edges extend into sealing contact with the downhole tubulars and discontinuities are present on the downhole tubulars, the inlays conform to the discontinuities to provide the sealing contact.
 17. The seal assembly of claim 14, wherein the seal body of the nose ring is threadingly coupled to the lockdown portion and further comprises a ring like lower base projecting axially downward from an end of a lowermost fold, wherein the lower base is in selective contact with a casing hanger. 